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Old 25 October 2015, 23:20   #20
ReadOnlyCat
Code Kitten

 
Join Date: Aug 2015
Location: Montreal/Canadia
Age: 48
Posts: 1,143
Quote:
Originally Posted by Toni Wilen View Post
3 planes should be possible, for example:

Code:
---2-3-1 ---2-3-1
--C-2-C- 3-C-1---
First line is bitplane DMA sequence, second is copper (C=copper instruction read, number = copper bitplane pointer write).
Damn, indeed. I should have known because when I worked out this sequence (on paper) for 5 bitplanes I took advantage of the fact that certain orderings produce less visual side effects because they occur at the right moment.

Quote:
Originally Posted by Toni Wilen View Post
Unfortunately it looks like 4 planes is possible by using similar interleaving but you'll hit hardware limit: write to any DMA pointer 1 cycle before same DMA pointer is used for DMA access: write does nothing..
Argh. This means I have to go over sequences I came up with.
Does the write really do nothing or is the written value only available after the DMA fetch?

If that's the latter then there is still hope.
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